mechau



R. MEcl-IAU GAnvANoMETER Feb. s, 1927.

2 Sheets-She/et 1 Filed Sept. 29. 1921 Fig. 1

Y' Jnvenlof.-

Feb. 8,1921. 1,616,754

1R. MEcHAu GALVANOMETER l Filed. sept. 29. 1921 2 sheets-sleet 2Patented Feb. 8, 19.27..

L UNITEDV STATES PATENT OFFICE.

:ROBERT ilmenau, or JENA, GERMANY, AssIGNoR To, Translation cam. zEIss,oF

' JENA, GERMANY. 'i A eAnvANoMErEn.

' Application mea september 29, 1921, serial No. 504,214, anain Germanyoctober 1s, 1920. f

l The object of the present invention is to providel a' sensitivegalvanometer which 1s sensitive in the highest possible degreeespecially` to mechanicalv strains, concussions or the like. s

According to the invention sucha galva-v nometer is obtained byproviding as a movable system a looped conductor, only fixed at both itsends, in connexion witha magnetic field, whereby the conductor is sodisposed 'that the vplane within which it travels is perpendicular tothe magnetic lines. Such a movable system cannot, of course, be entirelydisposed between the two poles of a magnet like the stretched conductorin string galvanometers because in the two halves of a loop' the currentflows in two directions being at least approximately opposite each'other, so that, when disposlng the `whole loop between the two poles ofa magnet, the

` loop would not receive an actuation of motion. With a-view toimparting to the loop an actuation it may, e.` g. beso disposed 1n thevicinity` of a margin of the pole-shoes that of two parts ofthe loop,transversely to the direction in which the deflection of the. loop is totake place, inlwhich parts the i current flows in approximately oppositedirections, ythe one lies outside the magnetic field.` 4

" However,- in, order to produce the magnetic field twomagnets shouldpreferably be disposed sidev by side in such a manner that the magneticlines of force between the poles f same transversely to the direction ofdeflection oftheA loop will be in the 'eld of tlie one magnet and asecond such part, in which the current flows at least approximately linthe opposite direction as is the case in the Arst part, in .the field ofthe second magnet. Thereby firstly a greater sensitiveness ofthegalvanometer `than with the use of only one magnet can be obtained, andsecondly it can .'beachieve'd that the property ofthe mateterials to beused for the 'manufacture of ,the loop conductor, viz,-to be always moreor less magnetic, either Apaaor diamagnetic, cannot have any detrimentalelect. When using a single magnet for the production of the ma etic eldthe said property of these materials makes itself conspicuous kof theloopand the amount of the deliection also dependon the loop consists.

. In ordento attain the largest possible senmaterial of which thevsitiveness the two fixing points of the loop should suitably'- bebrought together as closely as possible withfaview to thus minimizingthe 'resistance `of the loop to a; de-

flection from its normally vunenergized plane. s

v As fa rule,- the loop conductor is suspended, in whichl position aforce, telndingt)V restore the loop to its zeroposition, is exerted, in

addition to the elasticity inherent to the loop by the'weight ,of thelatter. However, the

arrangement'may, e. g. be also made in such a way that lthe loop isin ahorizontal posi- Ition or that it is upwardly directed from the fixingplace in a vertical plane. In both cases the weight ofthe loop does nothave a restoring effect upon the loop, and in the last-mentioned case iteven tends to an increase of the deflections. The position in spaceimparted tothe loop "from the olvltset` i' is thus decisive for theamount of sensitiveness vof the -galvanometer. Hence,l by causing themagnet system and the loop conductor to rotate about an axis which runshori.- zontally and parallelly to the loop plane, the sensitiveness 'ofthe galvanometer can be varied at will within certain limits-P byrotating the magnet system and the loop about this axis. l

Additionally it is suitable to dispose the loop. conductor rotatablyabout an axis which is perpendicular to the loop plane. It is therebypossible, apart from" the" caseof the*A loop plane being horizontal, toeffect in a simple manner, viz, by rotating the loop about thisv axis, acorrection of the lzero point. l The/fundamental idea of the inventionis ldiagrainmatically shown lin Fig. 1` of-the annexed drawing; Figs. 2to 5 show a constructional example, viz, Fig.y 2 is a lan view in which4the lid of the casing-has een taken off, Fig. 3 is a cross-section online 3-3 in Fig. 2, Fig. 4 is a front. view of a single part and Fig.. 5is an elevational view taken from the upward. In the case slown inbottom of Fig. 2 and looking Fig. 1 the magnetic field is produced by amagnet, indicated by the parts of its pole al and a2. The loop conductoris denoted by b.

In the example shown in Figs. 2te 5 the magnetic field is produced bytwo magnets c and d which are fixed in a casing e and so disposed that anorth-pole n and a south pole 8 each face each other. Between the polesof both magnets a loop conductor j' consisting of a thin metal band issuspended in a special protecting casing which is shut 0E on the sidesparallel to the loop plane by two glass plates g each and on its upperside by a plate 7L which does not conduct the electric current. For theobservation vof thede'flections' of the loop a microscope i is providedhaving an optical axis bent at right angles,

which microscope is adjusted to a mark f1 disposed at the' bottom end ofthe loop f.,

The illumination of this mark is effected through a window el disposedin a wall of the casing e. In order to be able to alter at will theposition of the loop 7' in space the casing e can be rotated about anaxis A-A, perpendicular to the loop plane, by means ot' a pivot y'within a sleeve k which is on its part rotatable about a horizontal axisBB, directed perpendcularly to the axis A-A, by means of a pivot r:1within a rsleeve m, fixed by a standard m1 on a base plate Z. For fixingthe sleeve m on the pivot k1 a setscreW o is employed. By rotating thecasing e with the pivot j in the sleeve c, viz, about the axis A-A, thepoint of suspension of the loop f, as observed in Fig. 3, moves totheleft or to the right and besidesowing to the dead weight of the loopf the mark f1 also deflects in the same direction thus changing itsposition' relatively to the axis of the microscope By rotating thecasing e with the pivot 701 in the sleeve/m., viz, about the axis B-B,the plane of the loop f is brought into an oblique position and', ontheloop be-` ing deflected by ak current, only a part of the weight ofthe loop f counteracts such a deie'ction, thus the sensitiveness of thegalvanometer beingv increased.

1. In a galvanometer a casing, two magnets disposed within the casingside by side in such amanner that the magnetic lines of the onemagnetare in the opposite direction to those of the other magnet, a holderlitted on the casing, and a loop-shaped conductor xed with its two endson this holder and being located with one of its members between thepoles of the one magnet and with the other of its members beA tween thepoles of the other magnet, the plane containing the said conductor beingperpendicular to the-magnetic lines 'of the y said magnets.l

2. In a galvanometer a casing, two magnets disposed within the casingside by side in such a manner-that the magnetic lines of the one magnetare in the opposite direction magnet, and a base plate, the said casingbeing disposed on this base plate rotatably about an axis directedhorizontally and parallelly to the plane of the loop, the planecontaining the -said conductor `being perpen= dicular to the magneticlines of the said magnets. l

3. In a galvanometer a casing, Itwo magnets disposed within the casingside by side in such a manner that the magnetic lines of the one magnetare in the opposite ydirection to those of the other magnet, a holderfitted on the casing, and a loop-shaped conductor fixed with its twoends on this holder and being located with one of its members betweenthe poles of the one magnet'and with the other of its members betweenlthe poles of the other magnet, the said holder being `rotatablerelatively to the base plate about an axis perpendicular tothe plane ofthe loop, the plane -containing the said conduc-v tor being'perpendicular tothe magnetic -lines of the said magnets. ff

4. In a galvanometer a casing,- two mag- ,f5

nets disposed within the casing side by side in such a manner that themagnetic lines of the one magnet are in thefopposite direction tothoseof the other magnet, a holder fitted on the-casing, aloop-shaped#conductor fixed located with one ot'v'its' members betweenthe of its members between the poles of the other `with its two ends onthis holder and beingI magnet, the plane containing the said conductorbeing perpendicular to', the magnetic lines of the saidmagnets, andamicroscope .fitted to thev said casing and allowing of' observing thesaid conductor.

ROBERT MECHAU. i'

